Sorry to hear about the foot problems -- you have to get this sorted out or it can get so bad you can't work. That would be a huge shame for all of us living vicariously through your posts!
I buddy of mine had terrible problems caused by standing on concrete and, as in your situation, mats were not an option.
He went through a lot of boots (about 8 brands over half a year) before his physiotherapist recommended this model made by Irish Setter.
The footbeds are removable, so on his physiotherapist's recommendation he took them out and put in a thick pair of gel insoles.